#setup
import random
import turtle
wn = turtle.Screen()
wn.colormode()
alex = turtle.Turtle()
turtle.screensize(500,500)
alex.speed(0)
alex.penup()
alex.goto(-250,-250)
alex.pendown()
wn.colormode(255)
alex.hideturtle()
#making the lines
times = 100
x = -250
y = 250
r = 255
b = 255
g = 175
for integer in range(times):
    alex.pencolor((r,g,b))
    alex.goto(x,-250)
    alex.goto(-250,y)
    alex.goto(-250,-250)
    x += 500/times
    y -= 500/times
    r -= 0.64
 #   g -= 0.01
 #   b += 0.01
    r = int(r)
    g = int(g)
    b = int(b)

Bezier